Supercharged at Last

[Durkin]

When I bought my 2003 Tahoe Z71, I knew that I would not be satisfied with the power of the stock 5.3 liter engine. Baseline stock dyno results run by AAA Muffler Auto Performance in Costa Mesa, CA at 90 MPH were: Rear Wheel Horsepower = 207; Torque = 277 ft lbs; RPM = 3,950; the speed limiter was on, but we did not hit it. You loose a lot of power with a 4WD because of the transfer case.

 

After a few months, I started tinkering with the truck and added JBA shorty headers, a Flowmaster 70 cat-back exhaust with a single 3” side exhaust, MSD sparkplug wires, and a Predator tune. All of this got about 35 more RWHP measured on the dyno. Of all the mods, I think the Predator made the most difference and a lot of that was in the shift improvements.

 

All along, I was researching superchargers; since the Tahoe is a truck not a sports car a roots or twin screw was the only choice and the choices were limited to: Whipple; Kenne Bell, and Magnacharger.

 

Kenne Bell was not a choice because they are not CARB approved for this truck and in California, that is a must have.

 

Whipple was interesting and the quietness of the twin screw was the strong suit; the off-setting negatives were all of the complexities of the installation; the need for additional injectors; a piggy back computer; and blowing fuel through the stock manifold, and the like. It is CARB approved.

 

The CARB approved Magnacharger Radix was my final choice even though it was more expensive. The installation is very clean and straight forward. The new intercooled manifold and larger fuel injectors are really well done and the supplied Superchips handheld tuner modifies the stock PCM program. It has a three year warranty on the supercharger and Magnacharger offers a power train warranty for an additional $200. The only drawback is the typical Roots whine when under boost. It seems to be the choice of most dealers like Chapman Supercharged Trucks. I did not take the warranty since I needed an excuse to beef up the transmission and rear end (just in case).

 

To quote Magnacharger, “These intercooled supercharger systems are complete with all components necessary for installation. Included in the kit are the patented cast aluminum intake manifold with equal length runners, intercooler core, coolant circulation pump, heat exchanger and all necessary hardware. Other components include new fuel injectors, fuel rails, factory “push lock connectors” and regulator adapter. The computer programmer communicates with the factory ECU for proper calibration of the supercharger system. Transmission shift points, line pressures and converter strategies are optimized for use with the increase in torque and horsepower”.

 

Since Arizona Speed and Marine does the work for Chapman, they were the logical choice to do the work and they did a great job on time. They also installed an Auto Meter boost gauge, fuel pressure gauge, and an air/fuel meter in a pillar pod. If you buy one from ASM ask for Ben Benavides, he took good care of me.

 

2003 Chevy Tahoe Z71 Dyno Results

RWHP RWT RPM

Supercharged 350 384 4,782

Stock 207 275 3,950

Increase 153 109

69% 39%

 

Tables are impossible here!

 

We were not sure if the Magnacharger program on the Superchips hand held tuner removed the speed limiter (I now know it does}, so we did not take it to 5,400 RPM or so to get the max readings, but I will do that in a few days and post it.

 

You can find pictures of the truck in my gallery at http://mct.truckmoxie.com/mygallery.asp?id=4951#mods

 

Regards,

 

Durkin

[1 Bad Burb]

WOW great improvements!!!! congrats man! now go out and kick someones azz!!!! u'll enjoy it sooooooo much!

Aj

[325]

I have also installed a Radix Magnacharger on a 5.3L 2003 Silverado. Two friends and I did it in 6 hours. It was probably the simplest thing I have ever done (only 2 minor glitches) and looks like a professional install.

 

I haven't noticed any whine on my setup under full boost. The only noise I notice at all is a rush of air (that's really not a good description).

 

The Superchip raises the RPM limiter by 400 and the speed limiter by 40 mph.

 

On your calculation of the gain in hp and torque between stock and supercharged, isn't some of that gain coming from the headers and cat back system? The fellow at Magnacharger (Magnuson) said I should expect 120 rwhp from the supercharger when installed on a stock engine. This seems to be a good estimate based on your dyno numbers (10 or 15 rwhp for the headers and cat back).

 

Sounds like you are enjoying your supercharger as much as I am. Good luck and keep us posted.

[Durkin]

Folks:

 

As promised, I went back to the dyno this morning and here are the rsults; at:

-- 102 MPH; 4,393 RPM; RWHP=335; RWT=401

-- 111 MPH; 4,782 RPM; RWHP=350; RWT=384

 

Note: I lowered the original torque numbers as they were way too high using a math adjustment to bring them into line; hence, some of the posts that follow are using the original data.

 

I have heard all sorts of factors for estimating HP and torque at the flywheel for a 4X4 to account for the transfer case loss and drive train loss, but I am estimating about 500 to 525 HP and about 575 to 600 FTLB of Torque at the flywheel. I would like to hear from any body who has better math.

 

Regards,

 

Durkin

[frdfandc]

You are going to have to figure that on a 2wd vehicle, there is an approximately 22-25% drivetrain loss. Now with a 4wd vehicle, its gonna be estimated at 28-30% drivetrain loss. So if you punch in the numbers

 

 

RWHP - 350

multiply that by 1.30

 

350 x 1.30 = 455 flywheel hp

 

TQ - 497

multiply that by 1.30

 

497 x 1.30 = 646 flywheel tq

 

I know it doesn't seem like a huge amount of flywheel hp compared to rwhp, but you have to remember that the roots style blowers make better torque numbers than hp numbers. If you had a centrifical blower on your truck, your hp numbers would be alot higher.

[GMC_DUDE]

Hey Durkin,

 

How is your truck's normal street manners now? My rig is a 2003 rcsb 4WD, 4.8L. I've added JBA headers, Flowmaster 70 single in -> dual out, and Flex-lite 290 fans, and have been looking to take it to the next level. I don't drag race, but I do drive the mountains (American Alps) on roads of steady 6 to 7% grade for up to 15 or so miles. Needless to say this rules out Nitrous and probably high stall torque converters. I also want to retain good around-town street drivability. The power is mostly for passing, merging on freeways (into 70+ MPH traffic via vintage 1964 on-ramps ), and going up above-mentioned grades. From your experience does the Radix sound like a good option?

 

Thanks,

 

GMC_DUDE

[Tommy'Z 6speed]

You can't multiply the RWHP and RWTQ numbers by 1.30 to calculate drivetrain loss because it's a flywheel HP/TQ loss of 30% not a rear wheel gain of 30%.

 

The real correction factor for 30% loss is 1.42857.

 

This means the flywheel HP is:

350RWHP X 1.42857 = 500 FWHP

or, in other words:

500 FWHP X .3 = 150 HP loss and 500 -150 leaves 350 RWHP

 

Flywheel Torque is:

497RWTQ X 1.42857 = 710 FWTQ

 

Hope this helps!

 

 

Great numbers by the way!

[Durkin]

GMC Dude:

 

I drove it all over Southeast NM arround the Continental Devide at about 7,000 ft and then across the Sierras on Interstate 8 and it was great; just dial in whatever speed you like on the cruise control and it will keep you there at any grade I encountered. It is great around town andas to passing and on-ramps ----heheheh says it all. Get one; you will love it.

 

Tommy'Z 6speed:

 

Glad your math produces the same result I got!

 

325:

 

I agree that all of the other stuff is additive and I think the previous mods were well worth it. Besides, it sounds better!!

 

Regards,

 

Durkin

[Durkin]

Folks:

 

After a lot of thought and such, I decided that the (hopefully) last performance mod would be a custom PCM tune. Westers or Nelson?

 

After even more thought and a lot of time reviewig stuff on forums like this, I chose Westers and it should be here in three days. Decided to buy a used PCM from Westers, so I cold keep mine in reserve if some sort of adjustments are required later.

 

Lyndon has been very helpfull and answered several questions very promptly; I was impressed!

 

In any event, it will be back to the dyno to see how Lyndon's tune works in comparison to the tune provided by Magnacharger. Will keep you posted!

 

Regards,

 

Durkin

[YZRider]

Durkin,

I am curious as to why you are changing the tune on your truck. Were there problems with the tune provided by Magnacharger? Were there driveability issues? I am asking because mine should be here in a week and I figured the programming provided with the unit was optimized for the specific truck it was going on.....maybe I'll have to call Lyndon too?

Steve

[Durkin]

Steve:

 

There are no problems at all; the Magnacharger tune is fine!

 

I just do not know where to quit on this thing.

 

Also, be sure to get the right copper plugs in one heat range colder, while you are at it; stock plugs are ok, actually, we left my AC Delco 41-932 platinums in as they were one heat range colder as a resut of the work I had done pre supercharger.

 

Regards,

 

Durkin

[atomoverride]

what was the price of your supercharger? and how come you didnt get the crome plated one?

[Durkin]

atomoverride:

 

The hardware was $5,050 and I did not think the polished version was worth another $600.

 

Regards,

 

Durkin

[Chad H]

How does this affect the life of the 5.3L? I dont want my motor blowing at like 65,000 just because it wears the motor down that quickly.

[Durkin]

Flodine:

 

I will let you know in 58,000 miles.

 

One can tear an engine up with or without a SC; depends most on your driving style. I expect 100K+ miles before having the blower rebuilt. But then again, I have never owned a car past 35,000 miles.

 

Regards,

 

Durkin